Fix for grayscale scans with gamma < 1.0

David Fox (dsfox@cogsci.ucsd.edu)
23 Jun 1999 10:07:14 -0700

Oliver Rauch <oliver.rauch@Wolfsburg.DE> writes:

> I uploaded xsane-0.26 to my homepage:
> http://www.wolfsburg.de/~rauch/sane/sane-xsane.html

Oliver,

I've found a bug whose most obvious symptom is that grayscale scans
with a gamma < 1.0 come out pure black. There are a couple of places
where gamma is declared as an int rather than a double (see below.)
These int declarations look odd, like they are a temporary solution to
some other problem. I haven't tested the resulting code extensively,
but grayscale with gamma < 1.0 does now work.

-- 
David Fox           http://hci.ucsd.edu/dsf             xoF divaD
UCSD HCI Lab                                         baL ICH DSCU


diff -ru xsane-0.26/frontend/xsane-scan.c~ xsane-0.26/frontend/xsane-scan.c
--- xsane-0.26/frontend/xsane-scan.c~	Fri May 14 12:22:25 1999
+++ xsane-0.26/frontend/xsane-scan.c	Wed Jun 23 09:56:40 1999
@@ -1661,7 +1661,7 @@
     }
     else if (xsane.scanner_gamma_gray) /* only scanner gray gamma function available */
     {
-     int gamma;
+      double gamma;
       /* ok, the scanner only supports gray gamma function */
       /* if we are doing a grayscale scan everyting is ok, */
       /* for a color scan the software has to do the gamma correction set by the component slider */
@@ -1731,7 +1731,7 @@
 
       if (xsane.xsane_color == 0) /* no color scan */
       {
-       int gamma;
+	double gamma;
 
         if (xsane.xsane_mode == XSANE_COPY)
         {



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